A jaw crusher of the general type to which this invention relates is disclosed in U.S. Pat. No. 3,166,259 to Archer et al, issued in 1965 and assigned to the assignee of this application. Such a crusher has a housing comprising upright side walls to which an upright stationary jaw is fixed at the front of the housing and between which a movable jaw is swingable towards and from the stationary jaw. The movable jaw is suspended at its upper end from a power driven eccentric shaft, while its lower end is rockably pivoted against a front edge of a toggle plate that has an opposite rear edge pivoted against a shiftable but normally fixed toggle beam. Biasing means react between the toggle beam and the lower portion of the movable jaw to urge them strongly towards one another and thus confine the toggle plate between them.
For adjustment of the movable jaw that varies the fineness of the product, each of the housing side walls has a way slot that is elongated in more or less horizontal forward and rearward directions, towards and from the stationary jaw; and the toggle beam, which extends across the housing, has opposite end portions slidably received in these way slots. At each side of the housing a hydraulic ram is connected between the housing and an end portion of the toggle beam for shifting the toggle beam along the way slots. Selected positions of the toggle beam are defined by shims which are inserted in the way slots behind the toggle beam and which transfer to the housing the rearward forces imposed upon the toggle beam. The toggle beam tends to remain engaged against the shims because the movable jaw is disposed at a downward and forward inclination such that its mass tends to swing it rearwardly about the eccentric shaft from which it is suspended. However, the toggle beam should be releasably locked against shifting forwardly away from the shims under the driving forces that the eccentric shaft imposes upon it through the movable jaw. It is also important that the toggle beam be releasably locked against vertical movement because, to provide clearance for its sliding, its heightwise thickness is somewhat less than the distance between the upper and lower surfaces of each way slot.
As disclosed by Archer et al, the toggle beam is releasably confined against shifting forwardly away from the shims by means of bolts which extend forwardly through a rear part of the housing and are threaded into the toggle beam. Other bolts extend downwardly through fore-and-aft elongated slots in the housing and are threaded into the toggle beam to releasably clamp it against the upper edges of the way slots.
While commercially successful, the arrangement disclosed by Archer et al had the important disadvantage that the weight of the toggle beam subjected the downwardly extending bolts to high tension forces which tended to elongate them, and they therefore had to be tightened from time to time to maintain the toggle beam firmly clamped to the housing and thus confined against rocking.
U.S. Pat. No. 3,473,744, to DeDiemar et al, issued in 1969 and also assigned to the assignee of this application, points out that substantial manual work is required for loosening and retightening the several clamping bolts for every readjustment of the position of the toggle beam. In addition to the horizontally extending hydraulic rams which effect shifting of the toggle beam, DeDiemar et al disclose a pair of upright hydraulic rams that are employed to release the toggle beam for shifting by the horizontal rams. The upright hydraulic rams cooperate with downwardly extending clamping bolts that are threaded into the toggle beam and are biased upwardly to their clamped conditions by means of a stack of Belleville washers surrounding each bolt and reacting between its head and the housing. Extension of the upright rams forces the clamping bolts downward against the biasing force of the Belleville washers, thus freeing the toggle beam from its clamped engagement against the upper edges of the way slots. While the arrangement disclosed by DeDiemar et al eliminated the need for laborious manipulation of the several upright clamping bolts, it achieved this advantage at the cost of two additional hydraulic rams and their control valves and the like. More important, the arrangement was found to be unsatisfactory in many applications because the Belleville washers could not exert a high enough clamping force upon the toggle beam to confine it against rocking under all conditions.
U.S. Pat. No. 4,165,044 to Batch, issue in 1979 and assigned to the assignee of this application, discloses an arrangement particularly intended for a large crusher having a large and heavy toggle beam which is difficult to lift and to move and hard to secure in place once shifted to a desired position of adjustment. In this case the toggle beam is configured to cooperate with wedges which are inserted from opposite sides of the crusher housing, between the toggle beam and the upper edge of each way slot, and which clamp the toggle beam against the lower edges of the way slots. Belleville washers and hydraulic rams are arranged to cooperate in driving the wedges to and from their clamped relationship with the toggle beam and the housing. With this arrangement the toggle beam is securely confined against rocking, but the hydraulic rams employed for adjustable shifting of the toggle beam must again be supplemented by at least two further hydraulic rams and their related apparatus.
The industry concerned with jaw crushers is an actively competitive one. Nevertheless, the above discussed patents represent what has heretofore been the most advanced state of the art. Thus it has clearly not been obvious how to provide a simple, inexpensive and efficient arrangement whereby the toggle beam of a large jaw crusher can be releasably locked in any desired position of its adjustment and thereby confined against both shifting and rocking without the need for difficult and time-consuming manual labor and also without involving the cost and complexity of hydraulic rams additional to those employed for the actual shifting of the toggle beam along the way slots.